//: concurrency/Philosopher.java
// A dining philosopher
package concurrency;

import java.util.concurrent.*;
import java.util.*;

import static net.mindview.util.Print.*;

public class Philosopher implements Runnable
{
    private Chopstick left;
    
    private Chopstick right;
    
    private final int id;
    
    private final int ponderFactor;
    
    private Random rand = new Random(47);
    
    private void pause()
        throws InterruptedException
    {
        if (ponderFactor == 0)
            return;
        TimeUnit.MILLISECONDS.sleep(rand.nextInt(ponderFactor * 250));
    }
    
    public Philosopher(Chopstick left, Chopstick right, int ident, int ponder)
    {
        this.left = left;
        this.right = right;
        id = ident;
        ponderFactor = ponder;
    }
    
    public void run()
    {
        try
        {
            while (!Thread.interrupted())
            {
                print(this + " " + "thinking");
                pause();
                // Philosopher becomes hungry
                print(this + " " + "grabbing right");
                right.take();
                print(this + " " + "grabbing left");
                left.take();
                print(this + " " + "eating");
                pause();
                right.drop();
                left.drop();
            }
        }
        catch (InterruptedException e)
        {
            print(this + " " + "exiting via interrupt");
        }
    }
    
    public String toString()
    {
        return "Philosopher " + id;
    }
} /// :~
